Many users of cell phones carry the cell phones on their belts or straps. Due to the decrease in size and weight of personal electronic devices, such as personal digital assistants, MP3 players, and small computers or communicators, these personal electronic devices can also be carried on a user's belt, purse strap, pant pocket or other belt-like structure. FIG. 1A diagrammatically illustrates a prior art belt or strap clip 10 which slips on the belt and FIGS. 1B, 1C and 1D diagrammatically illustrate prior art, “jaw style” clips 12 and 14. Some users prefer the jaw style clip of FIGS. 1B-1D because it provides better retaining characteristics and capture of the user's belt, or purse strap thereby preventing the loss of expensive cell phones and personal electronic devices. In FIG. 1A, main body unit 16 is adapted to be removably attached to the cell phone or personal electronic device 30 via button 18 shown in FIG. 2. Button 18 is attached to a cell phone or personal electronic device 30 and button 18 slides in and out of receiving passage 20 formed by body unit 16 and is releaseably locked or latched in receiving passage 20. The following patents describe prior art releasable button mounts: U.S. Pat. No. 5,597,102 to Saarikko (issued Jan. 28, 1997); U.S. Pat. No. 5,850,996 to Liang (issued Dec. 22, 1998) and U.S. Pat. No. 6,283,348 to Wang (issued Sep. 4, 2001).
FIG. 1B shows a prior art clip 12 with a metal leaf spring 22 having one end mounted to main body 24 and another end mounted to clip arm 26. Distal end regions 28, 30 of main body 24 and clip arm 26, respectively, form the “teeth” of the jaw and these teeth open and close based upon the user compressing the proximal end regions of both or either of main body 10 and clip arm 26 has shown by arrows A′-A″.
Prior art clip in FIG. 1A is made entirely of plastic and arm 11 opens passageway 13 based upon a force applied in direction B at the distal end of clip 10. The force opens the passageway 13.
FIGS. 1C and 1D also show an all plastic clip wherein the spring member 15 is U-shaped with one leg of the U attached to main body 17 and the other leg of the U attached to clip arm 19.
FIG. 3 diagrammatically illustrates another prior art design showing a metal leaf spring 22 having one leg 23 mounted into main body 24 and the other leg 25 mounted in clip arm 26. A plunger actuator 29 is biased outboard with respect to proximal end 31 of main body 24 via a metallic spring 27. Therefore, although many components of the prior art belt clip 12 are plastic (main body 24, clip arm 26 and plunger/actuator 29), two major components such as leaf spring 22 and bias spring 27 are metal. There is a growing need to eliminate all metal components in these belt clips due to the metal's adverse effect on the specific absorption rate (SAR) of radio frequency (RF) energy emitted by the cell phone and potentially directed into the user's body. More specifically, the metal may, in some rare occasions, focus or re-transmit or re-direct the radio frequency energy from the cell phone such that the energy effects the user's body. Presently, Federal Communications Commission (FCC) has regulations which limit specific absorption rates for cellular telephones when such cellular telephones are worn on the body of the user. The same is true regarding personal electronic devices. It is well established that an all plastic belt or strap clip does not have an adverse effect on specific absorption rate of the RF signal and therefore is potentially completely exempt from FCC regulations.
The problem with all plastic prior art jaw type belt clips (shown in FIGS. 1C and 1D) is that the small U-shaped spring member 15 fails prematurely and almost instantly because prior art all plastic designs were adopted from the very simple metal spring design (FIG. 1B) and just involve replacing the metal spring with a plastic spring. This adaptation of plastic from metal in the spring member, is fatal since plastic yields at much lower stress levels than metal and also has considerably lower strength than metal. The required geometry and relative proportions of a comparable all plastic spring are much different and larger than that of a similarly sized metal spring.